GB2338988A

GB2338988A - Closed crankcase ventilation

Info

Publication number: GB2338988A
Application number: GB9814085A
Authority: GB
Inventors: Eric Parlow; Gary Steven Antcliff; John Jerl Purcell
Original assignee: IVECO; Cummins Engine Co Ltd; New Holland UK Ltd
Current assignee: IVECO; Cummins Ltd; CNH UK Ltd
Priority date: 1998-06-30
Filing date: 1998-06-30
Publication date: 2000-01-12
Also published as: GB9814085D0

Description

1 2338988 Closed Crankcase Ventilation

Field of the invention

The present invention relates to the ventilation of the crankcase of an internal combustion engine.

Background of the invention

It is a common experience that gases in the combustion chambers of an internal combustion engine blow by the piston rings and enter the crankcase. Such so-called blow-by gases need to be vented to avoid a build up of pressure in the crankcase. Such gases cannot, however, simply be discharged into the ambient atmosphere as they would cause unacceptable pollution on account of the oil present in the crankcase. If the blow-by gases are returned to the engine intake system, the oil is burned eliminating the eventual pollution. This is not a practical solution however in as much as the oil reduces the turbocharger durability by converting to varnish at the high turbocharger temperatures. This varnish builds up on the turbocharger impeller gradually reducing its efficiency until performance problems occur.

To mitigate these problems, it is known to provide a filter to separate oil from the crankcase gases so that the oil may be returned to the crankcase before the gases are discharged or returned to the engine intake system. There are problems, however, in implementing such a system because of the limited space available to mount an oil separation filter and because of the expense of the additional pipework required.

- 2 Object of the invention The present invention accordingly seeks to enable closed crankcase ventilation to be implemented in a compact 5 and inexpensive manner.

Summary of the invention

According to the present invention, there is provided a unitary casting for covering a ventilation opening of an internal combustion engine crankcase, the casting comprising a chamber for housing a filter that serves to separate oil from discharged crankcase gases, a passage leading from the crankcase ventilation opening to the filter chamber, a passage for returning oil separated from the crankcase gases from the filter chamber to the crankcase and a gas outlet connection to enable filtered crankcase gases to be returned from the filter chamber to the engine intake system.

The invention achieves a compact and inexpensive installation by integrating the crankcase gas inlet and the oil return passage into a casting that houses the filter and is mounted directly onto the engine. The only additional pipework necessary is to connect the filter chamber to the engine intake system, for example to an engine turbo charger.

When fitted to an engine having valves operated by a camshaft mounted within the engine block, the casting incorporating the crankcase gas filter is preferably positioned to cover the camshaft bore in the engine block, thereby providing a saving on an end cap for the camshaft bore.

The filter mounted in the filter chamber in use of the invention may be a coalescence filter, an electrostatic filter or a vortex filter.

Brief description of the drawings

The invention will now be described further, by way of example, with reference to the accompahying drawings, in which:

Figure 1 is a perspective view from one side of a unitary casting of the invention, Figure 2 is a perspective view of the casting in Figure 1 as viewed from the other side, Figure 3 is a section that passes through the filter chamber and illustrates the method of operation of the closed crankcase ventilation, and Figure 4 shows the casting of Figures 1 to 3 fitted to an engine.

Detailed description of the preferred embodiment

Referring first to Figure 4, this shows a diesel engine 110 operating with a high pressure common rail (HPCR) fuel system. Most of the parts of the engine will be recognised by the person skilled in the art and they need not therefore be described in detail. The engine is a push rod engine that comprises an engine block 111, a cylinder head 112 and a rocker cover 114. An intake manifold 116 supplies air to the engine cylinders and a common fuel rail 118 connected to injectors supplies fuel. The fuel in the fuel rail 118 is pressurised by means of a pump unit 122. A casting 10 of the present invention is bolted onto the side of an engine by means of bolts that pass through various fixing holes designated 12 in Figures 1 to 3.

The engine 110 has a camshaft mounted in a bore in the engine block 111 and a crankshaft ventilation opening that is located above the camshaft. The engine block also has an opening adjacent the camshaft bore for returning oil to the crankcase that is separated from the crankcase gases by the oil filter of the closed crankcase ventilation system.

Referring now to Figures 1 to 3, the casting 10 includes a cover 22 that closes the camshaft bore in the engine block, a filter chamber 16, a passage 14 that overlies the crankcase ventilation opening and leads to the filter chamber and a passage 18 that overlies the oil return opening and leads to the bottom of the filter chamber 16.

The filter chamber 16 also has an outlet 20 for filtered gases to be returned to the engine intake system.

As can be seen from Figure 1 and 3, the outlet 20 is formed as part of a removable top 26 secured to the filter chamber 16 by means of screws 28 and serving to retain a filter element 32 within the filter chamber 16. The filter element is made of two cylinders, the inner cylinder being a coalescence filter and the outer cylinder an aerosol element. The filter can have other forms and may alternatively be an electrostatic filter or a vortex filter The top 26 includes a pressure control 36 that limits the pressure in the filter chamber 16 and a rion-return valve 38 that prevents air from being drawn into the crankcase from the intake system. A cover 30 secured to the top 26 by means of screws 24 provides access to the two valves 36 and 38.

In use the casting 10 is bolted to the engine and a seal is achieved around the passages 14 and 18 and around the camshaft bore by means of suitable O-rings or gaskets 40, 42 that are shown in Figure 2. Crankcase gases enter the filter chamber 16 from the crankcase through the passage 14 which includes a sharp 90 turn. This turn in itself results in some of the oil carried by the crankcase gases being separated out and falling to the bottom of the filter chamber 16. The gases then pass through the aerosol element and the coalescence element of the filter which separate oil from the crankcase gases. The oil drops to the bottom of the chamber 16 and flows back into the crankcase through the passage 18 while the filtered air is passes through the valves 36 and 38 to the outlet connection 20 from which it is returned by means of an external pipe to the intake system, preferably to the turbocharger.

It will be seen from the foregoing description that by integrating the air and oil passages into a unitary casting that can be bolted directly onto the engine block, the invention provides a compact construction that can be assembled rapidly. There is little additional cost involved as it is possible to make use of already existing tapped holes to bolt the casting to the engine block and if the casting doubles as a cover for the camshaft bore, then still further savings are made in dispensing with the cover and its seals and fixings.

Claims

1. A unitary casting for covering a ventilation opening of an internal combustion engine crankcase, the casting comprising a chamber for housing a filter that serves to separate oil from discharged crankcase gases, a passage leading from the crankcase ventilation opening to the filter chamber, a passage for returning oil separated from the crankcase gases from the filter chamber to the crankcase and a gas outlet connection to enable filtered crankcase gases to be returned from the filter chamber to the engine intake system.

2. An internal combustion engine fitted with a casting as claimed in claim 1, wherein the engine has valves operated by a camshaft mounted in a bore in the engine block and wherein the casting incorporating the crankcase gas filter is positioned to cover the camshaft bore.

3. An engine as claimed in claim 2, wherein the crankcase ventilation opening is positioned in the engine block above the camshaft bore.

4. An engine as claimed in claim 2 or 3, further comprising a filter located within the filter chamber, wherein the filter is a coalescence filter.

5. An engine as claimed in claim 2 or 3, further comprising a filter located within the filter chamber, wherein the filter is an electrostatic filter.

6. An engine as claimed in claim 2 or 3, further comprising a filter located within the filter chamber, wherein the filter is a vortex filter.

7. A unitary casting for covering a ventilation opening of an internal combustion engine crankcase, constructed substantially as herein described with reference to and as illustrated in the accompanying drawings.